Molecular phylogeny of the Trichodactylus fluviatilis Latreille, 1828 (Brachyura: Trichodactylidae) species complex

The freshwater crab Trichodactylus fluviatilis Latreille, 1828 presents considerable morphological variability as well as a wide geographical distribution. Such variability has generated in some cases doubts concerning the identity of the species. We investigated the diversity of this taxon, testing the hypothesis of species-level diversity using molecular tools. The analyzed material was obtained from fresh material collected during recent field expeditions and from existing crustacean collections. We also generated mitochondrial sequences (16S rRNA and COI) from 105 samples. The molecular analysis (Bayesian Inference and Maximum Likelihood) showed four main lineages that present considerable genetic divergence between them and a close relationship with distinct hydrographic basins and geographical regions. Other species of Trichodactylus Latreille, 1828 were positioned among the lineages of T. fluviatilis. Our results demonstrate that T. fluviatilis does not form a monophyletic group. It should be therefore considered a species complex, which requires taxonomic adjustments.